science

The total number of peer-reviewed scientific papers dedicated to cannabis, and the therapeutic use of cannabis in particular, has increased exponentially in recent years, according to data published the journal Population Health Management.

Israeli researchers assessed trends in the number of scientific publications specific to cannabis as compared to all scientific publications during the years 2000 to 2017. They reported: “The overall annual number of scientific publications … increased 2.5 times between 2000–2017 from 531,664 to 1,282,229. In contrast, the corresponding number for publications on cannabis increased 4.5 times … and increased 9-fold for publications on medical cannabis.”

Overall, authors identified just over 29,000 cannabis-centric scientific papers published during the study period, with over 3,300 of those dedicated to the subject of medical marijuana. Papers specific to medical cannabis were most likely to address its use in the treatment of HIV, chronic pain, multiple sclerosis, nausea, or epilepsy.

Over 60 percent of the papers were classified as “original research,” and 66 percent of all scientific papers originated from authors in the United States.

Commenting on the findings, NORML’s Deputy Director Paul Armentano said: “These results stand in stark contrast to the popular narrative that we lack adequate scientific understanding of cannabis and its effects. In fact, ample studies already exist to contradict cannabis’ federal, schedule I status as a substance without medical utility, lacking acceptable safety, and possessing a high potential of abuse.”

He added, “More clinical research is welcome, but unfortunately science has never driven marijuana policy. If it did, the United States would already have a very different policy in place.”

An abstract of the study, “Trends in publications in medical cannabis from the year 2000,” appears online here.

The National Academy of Sciences, Engineering, and Medicine released a comprehensive report today acknowledging that “conclusive or substantial evidence” exists for cannabis’ efficacy in patients suffering from chronic pain, and sharply criticized longstanding federal regulatory barriers to marijuana research – in particular “the classification of cannabis as a Schedule I substance” under federal law.

Authors of the report also addressed various aspects of marijuana’s effect on health and safety, acknowledging that the substance may pose certain potential risks for adolescents, pregnant women, and for those who may be driving shortly after ingesting cannabis. In each of these cases, these risks may be mitigated via marijuana regulation and the imposition of age restrictions in the marketplace.

Commenting on the report, NORML Deputy Director Paul Armentano said:

“The National Academy of Science’s conclusions that marijuana possesses established therapeutic utility for certain patients and that it possesses an acceptable safety profile when compared to those of other medications or recreational intoxicants are not surprising. This evidence has been available for some time, yet for decades marijuana policy in this country has largely been driven by rhetoric and emotion, not science and evidence.

“A search on PubMed, the repository for all peer-reviewed scientific papers, using the term ‘marijuana’ yields over 24,000 scientific papers referencing the plant or its biologically active constituents — a far greater body of literature than exists for commonly consumed conventional drugs like Tylenol, ibuprofen, or hydrocodone. Further, unlike modern pharmaceuticals, cannabis possesses an extensive history of human use dating back thousands of years, thus providing society with ample empirical evidence as to its relative safety and efficacy.

“Today, 29 states and Washington, DC permit physicians to recommend marijuana therapy. Some of these state-sanctioned programs have now been in place for nearly two decades. Eight states also permit the regulated use and sale of cannabis by adults. At a minimum, we know enough about cannabis, as well as the failures of cannabis prohibition, to regulate its consumption by adults, end its longstanding criminalization, and to remove it from its Schedule I prohibitive under federal law.”

The report marks the first time since 1999 that the National Academy of Sciences has addressed issues surrounding marijuana and health. Authors reviewed over 10,000 scientific abstracts in their preparation of the new report.

A new study on marijuana appeared in Journal of the American Heart Association. These are interesting data, but we have to interpret them very carefully.

Sure, we know cannabis can raise heart rate briefly, but most users develop tolerance to the effect. We’ve also seen (in a much larger sample) that it doesn’t increase mortality rates even among survivors of heart attacks.

But the new study made the news anyway. Investigators specifically searched a French database where physicians are legally bound to report any drug-related case that they view as “leading to temporary or permanent functional incapacity or disability, to inpatient hospitalization or prolongation of existing hospitalization, to congenital anomalies, or to an immediate vital risk or death.”

They then looked for cannabis users and found a shade less than 2,000 in the past 5 years. It’s impossible to know what that number means without knowing the number of people these physicians saw or how many patients used cannabis and did not end up reported to this database.

They then found a whopping 35 of these who had cardiac complications. It is impossible to know what to make of this number without knowing the number of cannabis users in France, which the authors report is 1.2 million. If you divide 35 by 1.2 million you get roughly .00003. I’m guessing that not all these cannabis users went to the doctor and not every person who used cannabis and had cardiac complications fessed up to the doctor, so let’s say that we’re off by two orders of magnitude. Let’s give the prohibitionists the benefit of the doubt and multiply by 100. That’d put the rate of problems up to .003.

If those are the chances of having cardiac complications as a French cannabis user, my first thought is that using cannabis protects people from cardiac problems. We need a comparison group of people who don’t use cannabis to know their rate of cardiac problems, but, as the authors point out, we simply don’t have those data. The closest estimates were 57 per 10,000 people, based on another study, which is .0057, or almost twice as bad as the rate among the cannabis users (after our generous overestimation). I’m not going to hold my breath for the the headline, “Cut your heart disease in half with cannabis.”

In short, this study tells us a lot about what kinds of cardiac complications appeared in people who were reported to the French government for cannabis-related problems, but tells us little about the link between cannabis use and cardiovascular disease.
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A recent headline reads: “Can Marijuana Kill You? German Scientists Say Yes.” The article focuses on a study of two (count ‘em, two!) young men who died while they had detectable levels of THC in their blood. I take a lot of pleasure in this kind of melodrama. If prohibitionists are stooping this low, we must really be frightening them. (It’s not completely pharmacologically ridiculous. Marijuana does increase heart rate. In fact, it can jack up heart rate almost as much as an espresso or energy drink. Maybe if you already had a weak heart and a coffee and a bong hit, well, something might happen.)

But I want to point out that we should actually expect literally thousands of reports like this. We should hear about lots of people who have heart attacks on the same day that they commune with the plant. It’s not because cannabis causes heart attacks. It’s simple chance.

I hate for my first blog as Chair of The Executive Board to be this nerdy, but I’ve been teaching statistics for more than 20 years. If that doesn’t make me a nerd, I’m not sure what would. But given how many people use cannabis daily and how many heart attacks occur in the United States, it’s actually a miracle that we haven’t heard about this kind of thing before. We also should expect to hear it a lot more often.

According to the National Survey on Drug Use and Health, roughly 7,600,000 Americans (over age 12) used marijuana daily or near daily in 2012. In addition, the Center for Disease Control suggests that about 715,000 of us have heart attacks in a year. (Let’s assume those under age 12 are probably not grabbing their chests with a myocardial infarction too often.) In addition, let’s guess that the United States has about 280 million people over age 12. It’s hard to know the exact number, but that’s probably in the ballpark.

With this in mind, we can predict how many people should have a heart attack the same day that they used cannabis simply by chance. That is, even if these two things had nothing to do with each other, we should expect some folks to have a heart attack the same day that they used cannabis just by accident.

Okay. It’s going to get nerdy here, but this is comparable to asking simpler questions. If I had a dime and a nickel, I might want to know what the chances are that I’d flip heads on both. I flip heads 1 out of 2 times on average for the dime, for a probability of .5. Then I flip heads on the nickel 1 out of 2 times on average, also for a probability of .5. So the chances of flipping heads on both is .5 * .5 for .25. So we’d expect to get heads on both coins about 1Ž4 of the time. If I flipped both coins 100 times, I’d get around 25 pairs of heads. Note that there’s nothing causal here. The nickel doesn’t know what the dime did. It doesn’t want to be like the dime. It’s not that the dime caused the nickel to flip heads.

So it’s the same deal for the cannabis-related heart attacks. If 7.6 million people use cannabis daily out of 280 million relevant Americans, that’s a probability of .0271. And if 715 thousand of 280 million have heart attacks, that’s a probability of .0026. Multiply these the same way we did with the probabilities for flipping heads (.0271 * .0026 = .00007). Now .00007 is a dinky number. If there were only 100 people in the country, we wouldn’t expect any of them (well, .007) to have a heart attack and smoke cannabis on the same day. But we’re talking about 280 million people here. So we’d expect .00007 * 280,000,000, = 19,600. That’s over 19,000 heart attacks.

So the question isn’t, “How did these two guys die of a heart attack with THC in their blood?” It should be, “Where are the other 19,598 guys who should have had heart attacks with THC in their blood?” In fact, the absence of this many cannabis-related myocardial infarctions inspired my wife to ask, “Does cannabis protect the heart?”